Disc brakes normally use first and second guide pins that are retained in first and second bores in a support member that is fixed to the frame of a vehicle. In such disc brakes, the support member receives the spaced apart first and second guide pins to allow the caliper to slide and allow corresponding first and second friction pads to engage with a rotor to effect a brake application. The following U.S. Pat Nos. 5,526,904; 5,749,445; 5,810,122; 5,934,416 and 6,454,056 may be considered typical of such disc brakes. Basically during a brake application, the first and second guide pins slide in the first and second bores as a reaction to a force developed by pressurized fluid being presented to an actuation chamber that acts on an actuation piston to directly move the first friction member toward a rotor. The reaction force is received by the caliper and as a result moves a second friction member toward and into engagement with the rotor during the brake application. On termination the presentation of pressurized fluid to the actuation chamber, the first and second friction members move away from the rotor to establish a running clearance. In such disc brakes the caliper is a component that adds considerable weight to the disc brake in addition for a need to easily slide toward and away from the rotor. If either the first or second friction members do not move away from the rotor brake, drag occurs which can cause undesirable wear of both the friction members and rotor. It is known to utilize the resiliency of a seal associated with the actuation piston to assist in the moving the first friction member away from the rotor. Unfortunately, the second friction member is not directly moved away from the rotor but must rely on knock back by the rotor to eliminate brake drag. Brake manufacturers have attempted to reduce brake drag by developing low slide force calipers, however, the components of current disc brakes require tight tolerance to maintain desired operational capabilities. If such tolerances are not maintained, a perpendicular relationship between the guide pins and rotor is not achieved and caming can occur that causes pin binding that can result in high slide forces. It has been suggested that slide forces could be reduced by increasing the clearance tolerance between the guide pins and bores in the fixed support to provide for a free sliding structure. Evaluation of this type structure indicated that noise was created as the pins rattled in the bores when the vehicle traveled on a road having an uneven surface. Rubber insulators that surrounded the guide pins were added to attenuate the noise created by the rattle, unfortunately, this solution reduced the free sliding ability of the caliper and as a result did not completely solve the problem.
It had been disclosed in U.S. Pat Nos. 3,113,643, 4,155,431, and 6,000,506 that the caliper could remain stationary by locating pistons one both sides of the rotor that move the friction members into engagement with a rotor to effect a brake application.
When disc brakes are used for large trucks it has been disclosed that an actuator may include a wedge member such as disclosed in U.S. Pat. No. 5,249,648. This structure functions in an adequate manner but has not been adaptable for use in automobiles.